Rossano Rossino

Genetic testing improves the diagnosis of adult type hypolactasia in the Mediterranean population of Sardinia

Objective:Recently, the C/T-13910 polymorphism on chromosome 2q21 in North-European populations has been found completely associated with lactase activity and its genetic typing proposed as first-stage screening test for adult hypolactasia. However, the C/T-13910 variant in some sub-Saharan African groups is not a predictor of lactase persistence. In this work, we wanted to verify if in the Mediterranean island of Sardinia, located in Southern Europe, the C/T-13910 polymorphism may be useful or not for the diagnosis of adult type hypolactasia.Design:Validation study of a genetic testing for adult type hypolactasia in Sardinians.Setting:Brotzu Hospital and Microcitemico Hospital, Cagliari, Italy.Subjects:The sample consisted in 84 Sardinian individuals (63 women and 21 men; range 20–73 years) selected from a group of 832 patients.Methods:Genetic testing was compared to an improved test obtained by a combination of different breath hydrogen tests and clinical assessment.Results:We found that all 49 individuals with lactose malabsorption, demonstrated by a combination of different breath hydrogen tests and clinical assessment, carried the C/C-13910 genotype associated with lactase non-persistence, 23 individuals with lactose normal absorption carried the C/T-13910 genotype associated with lactase persistence and only one person with the above phenotype showed a discordant C/C-13910 genotype. The genetic testing showed very high sensitivity, specificity, positive and negative predictive values of 100, 95.8, 98 and 100%, respectively.Conclusions:Sardinians, unlike some ethnic groups in sub-Saharan Africa, show the same genetic association of hypolactasia with the C/T-13910 variant as other North-European populations. The genetic testing for the C/T-13910 variant may contribute to improving the diagnosis of adult type hypolactasia.

Decline of lactase activity and C/T-13910 variant in sardinian childhood

Objectives: Our study aims to determine the age of onset of adult-type hypolactasia in Sardinians, and to establish the age at which genotyping of the C/T-13910 variant can be used reliably in the diagnosis of lactose malabsorption. Patients and Methods: A lactose breath hydrogen test was given to 383 randomly selected patients, from 3 to 19 years old. Results: The C/C-13910 genotype was found in 90% of patients; the frequency of the positive lactose breath hydrogen test increased with age and reached a prevalence of 85% at 9 years. Conclusions: In Sardinians, adult-type hypolactasia becomes phenotypically evident in all individuals older than 9 years, suggesting that this should be considered the minimum age at which the genetic test for lactase nonpersistence should be applied.

Characterization ofDasypyrum villosum (L.) Candargy chromosomal chromatin by means ofin situ restriction endonucleases, fluorochromes, silver staining and C-banding

The distribution of C-banded heterochromatin was determined in an inbred line ofDasypyrum villosum. Practically no difference in chromosome morphology or band distribution could be observed within the chromosomes of the same pair. Heterochromatin bands, revealed by Giemsa banding, were characterized by means of their differential reaction to fluorochromes, silver staining andin situ digestion with different restriction endonucleases. The results clearly indicate that inD. villosum two different classes of heterochromatin with different chromosomal local-ization exist: one is evidenced by both C-banding and DAPI staining and has mainly telomeric distribution, the other is evidenced only by C-banding and has mainly centromeric distribution.

The Efficiency of In-situ Hybridization on Human Chromosomes with Alphoid DNAs is Enhanced by Previous Digestion with AluI and TaqI

Centromeric alphoid DNAs of human chromosomes 6, 9, 16 and Y were employed to obtain information on the molecular mechanism(s) determining cytological effects produced by digestion in situ with AluI and TaqI restriction enzymes, possibly related to the structure of the above-cited areas. The following cytological and biochemical experiments were carried out using the above-mentioned alphoid sequences as probes: (1) standard in-situ hybridization and in-situ hybridization after chromosome cleavage with AluI/TaqI, and (2) filter hybridization on the DNA fractions obtained from the material solubilized and that retained on the slides after digestion in situ with AluI/TaqI. Biochemical data show that cleavage of alphoid DNAs is not prevented by the peculiar organization of centromeric heterochromatin, but such cleavage is not necessarily followed by complete DNA solubilization. The analysis of alphoid sequence cleavage in naked genomic DNA as well as during digestion of fixed chromosomes shows that (1) AluI cuts more efficiently than TaqI, (2) DNA fragments as large as 3–5 kb can be solubilized, and (3) DNA fragments of the same size are found in both fractions of DNA, i.e. that retained on the chromosomes as well as that solubilized from chromosomes. Cytological data show that previous chromosome digestion, mostly with TaqI, increases the hybridization signal area, suggesting that this fact might be due to (1) chromatin reorganization produced by enzyme attack and/or (2) the presence of alphoid DNAs which might be restricted not only to the kinetochore area but also to para/peri-centromeric heterochromatin. Lastly, centromere DNA solubilization as a consequence of restriction enzyme cleavage seems to vary from chromosome to chromosome, thus suggesting that centromeric regions do not represent a homogeneous class of constitutive heterochromatin.

Frequency of the thiopurine S‐methyltransferase alleles in the ancient genetic population isolate of Sardinia

Background:  Thiopurine S‐methyltransferase (TPMT) is an enzyme involved in the normal metabolic inactivation of thiopurine drugs. Patients with intermediate or no TPMT activity are at risk of toxicity after receiving standard doses of thiopurine drugs and it was shown that inter‐individual differences in response to these drugs is largely determined by genetic variation at the TPMT locus.

The DNA fragments produced by AluI and BstNI digestion of fixed mouse chromosomes

AluI and BstNI restriction endonucleases were used to study cytological and biochemical effects on centromere DNA in fixed mouse chromosomes. These enzymes were employed, as it is known that AluI is incapable of attacking major satellite DNA, contrary to BstNI that is known to cut this DNA fraction into monomers of 234 bp. After digestion in situ, electrophoretic analysis was carried out to characterize the DNA purified (1) from the material remaining on the chromosomes and (2) from the material solubilized from chromosomes. The DNA was then transferred to a nylon filter and 32P-labelled major satellite DNA was used as a probe for hybridization experiments. Other preparations were simply stained with Giemsa after digestion in situ with AluI and BstNI. Our results show that although restriction endonuclease cleavage primarily depends on DNA base sequence, this factor is not always sufficient to explain nuclease-induced cytological effects. In fact, the structural organization of peculiar regions such as the centromeres of mouse chromosomes might affect cleavage efficiency when restriction enzyme digestion is performed in situ.

Anti-Actin IgA Antibodies Identify Celiac Disease Patients with a Marsh 3 Intestinal Damage among Subjects with Moderate Anti-TG2 Levels

A new diagnostic tool (algorithm-1) for coeliac disease (CD) permitting the diagnosis without performing the duodenal biopsy has been recently proposed by the European Society for Paediatric Gastroenterology, Hepatology, and Nutrition (ESPGHAN). It combines symptoms associated with CD, high anti-transglutaminase type 2 antibody (anti-TG2) levels, anti-endomysium-IgA antibodies (EMA), and at-risk HLA. Our aims were (i) to evaluate retrospectively in 227 individuals (149 CD patients and 78 controls) the algorithm-1, (ii) to reduce the number of duodenal biopsies among CD patients for whom algorithm-1 is not applicable through the addition of antiactin IgA antibodies (AAA-IgA), and (iii) to evaluate prospectively algorithm-1 and AAA-IgA in 50 patients with suspected CD. Algorithm-1 identified 70 out of 149 CD patients with Marsh 3 lesions. Adding AAA-IgA to the remaining patients with anti-TG2 levels comprised between 4 and 10 times upper limit of normal (ULN) allowed the detection of further 20 patients with a Marsh 3 damage. In our prospective study, algorithm-1 identified 23 out of 50 patients, whilst further 7 were recognized adding AAA-IgA. We confirm that algorithm-1 may avoid the duodenal biopsy in many CD patients and underscores the usefulness of AAA-IgA in reducing the number of duodenal biopsies in patients with moderate anti-TG2 levels.

Ring chromosome 14 mosaicism: an unusual case associated with developmental delay and epilepsy, characterized by genome array-CGH.

Ring Chromosome 14 Mosaicism: An Unusual Case Associated With Developmental Delay and Epilepsy, Characterized by Genome Array-CGH Anna Lisa Nucaro,* Melania Falchi, Tiziana Pisano, Rossano Rossino, Francesca Boscarelli, Giusi Stoico, Angela Milia, Caterina Montaldo, Carlo Cianchetti, and Dario Pruna INN-CNR, Cittadella Universitaria, Monserrato, Cagliari, Italy Clinica di Neuropsichiatria Infantile, Azienda Ospedaliero-Universitaria, Cagliari, Italy Dipartimento di Scienze Pediatriche e Medicina Clinica, Azienda Ospedaliero-Universitaria, Cagliari, Italy Dipartimento di Scienze Chirurgiche e Odontostomatologiche, Universit a di Cagliari, Cagliari, Italy Technogenetics Bouty, Company, Sesto San Giovanni, Italy Dipartimento di Biologia Sperimentale, Universit a di Cagliari, Cagliari, Italy

High frequency of low-risk human leukocyte antigen class II genotypes in latent celiac disease.

Human leukocyte antigen (HLA) class II genotypes in latent celiac disease, a clinical variant of celiac disease (CD) have been scarcely studied. The aim of this work was to investigate whether latent CD and CD share similar frequencies of HLA class II genotypes. HLA class II genotypes of CD patients compared with controls were subdivided in the following at-risk groups: DQB1*02/DQB1*02 (43.0%, odds ratio [OR] 8.02, p < 0.0001), DQB1*0302/DQB1*02 (12.2%, OR 2.77, p = 0.0002), DQB1*02/DQB1*X (39.2%, OR 1.23, p = 0.1903), DQB1*0302/DQB1*X (3.4%, OR 0.35, p = 0.0064) and DQB1*X/DQB1*X (0.8%, OR 0.01, p = 0.0001) where X is neither DQB1*0302 nor DQB1*02. Next, HLA class II genotypes of 21 latent CD patients were compared with the above at-risk groups. Only one latent CD patient (4.8%) was found in the high risk DQB1*02/DQB1*02 group, three (14.3%) were DQB1*0302/DQB1*02, one (4.8%) was DQB1*0302/DQB1*X and the remaining 16 (76.2%) showed the DQB1*02/DQB1*X genotype. Noteworthy, the only 1 patient with the DQB1*02/DQB1*02 high risk genotype did not carry the DR3-DQB1*02/DR3-DQB1*02 or the DR3-DQB1*02/DR7-DQB1*02 but the uncommon DR3-DQB1*02/DR4-DQB1*02 genotype. These data suggest that latent CD is prevalently associated with low-risk HLA class II genotypes.

Turner syndrome mosaicism: an unusual case with a de novo large dicentric marker chromosome: mos 45,X/46,X, ter rea(X;X)(p22.3;p22.3)

X/X translocations are quite rare in humans. The effect of this anomaly on the phenotype is variable and depends on the amount of deleted material and whether the chromosomes are joined by their long or short arms. We report an unusual case of Turner syndrome mosaicism in a 16-year-old girl, who was referred to our Institute for primary amenorrhoea associated with short stature. Endocrine evaluation revealed hypergonadotropic hypogonadism, which required a study of the karyotype. Cytogenetic analysis, performed on peripheral blood leucocytes, showed a mos 45,X/46,X,ter rea (X;X)(p22.3;p22.3) de novo karyotype. The prevalent cell line was 45,X (90% cells). A second cell line (10% cells) showed a very large marker chromosome, similar to a large metacentric chromosome. FISH (fluorescent in situ hybridisation) and molecular analysis revealed that the marker chromosome was dicentric and totally derived from the paternal X chromosome.